(1) Field of the Invention
The present invention relates to a valve. More particularly the invention relates to a valve that has the capability to open a flow path rapidly without the requirement for rapid actuation or excessive size. The valve is highly desirable for use in various types of launch systems.
(2) Description of the Prior Art
A number of launch systems are being considered which require the rapid opening of a pressurized flow path to eject a vehicle.
The only known way to achieve instantaneous opening of a flow path is to utilize a burst valve. However, a burst valve has an acoustic disadvantage. The member which bursts must be replaced every time it is used, and burst valves are not normally designed for large flow paths due to the complexity of holding back a large force prior to actuation. In addition, the portion of the valve which bursts must withstand varying pressures when the ejection barrel is open to the interior of the ship and the sea side of the valve is subjected to varying submergence pressures.
Standard valves are designed such that their opening provides a very small flow path when they first start to open. Their flow paths increase to their full potential on a timed basis, dependent on their opening rate. While the primary feature desired is that of rapid opening, it is also advantageous to utilize a valve which minimizes flow losses and is not excessively large. Ball valves minimize flow losses when open; however, they become quite large when designed for large flow paths. Gate valves have higher flow losses and they also become quite large when designed for large capacity flows. Spool valves or slide valves are compact designs. However, they normally take longer to open than ball or gate valves.
Any valve can be opened faster simply by increasing the operating speed of its operator, or by developing a mechanical advantage between the valve's actuator and its operating surface. The disadvantage to faster operation lies in the increased complexity or size of the operator and noise associated with the faster motion of mechanical parts.
Present launch systems utilize a slide valve to seal the launch tube from the launch tube ejection system. The slide valve is a linear actuated cylinder within the launch tube which, when actuated, opens slots in the launch tube to a tank which is pressurized by the launcher's ejection system. Such valve is fully satisfactory when used with the existing system as the slide valve is opened prior to the initiation of the ejection system and tank pressurization. Therefore, there is no need to operate the valve rapidly. If the slide valve's operator was modified to open the valve rapidly, it would have the acoustic problems associated with rapid actuation and only a small area would first be opened. Therefore, the initial flow through the valve would have a high velocity and launch would be effected by a gradual build up of pressure behind the device that was being launched. If a rotational slide valve were developed it would require seals between each slot in the slide valve cylinder and barrel when the assembly is in the closed position. Such a sealing system is extremely complex. In addition, the seals are susceptible to damage when the valve is rotated to its actuated position.